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    <script>
        //0. Number.EPSILON 是 Javascript 表示的最小精度
        //EPSILON 属性值接近于 2.2204460492503130808472633361816E-16
        console.log(0.1 + 0.2 === 0.3);
        function equal(a, b){
            if(Math.abs(a-b) < Number.EPSILON){
                return true
            }else{
                return false
            }
        }
        console.log(0.1 + 0.2 === 0.3);
        console.log(equal(0.1 + 0.2, 0.3));

        //1. 二进制和八进制
        let b = 0b1010
        let o = 0o777
        let d = 100
        let x = 0xff

        console.log(b);//10
        console.log(o);//511
        console.log(d);//100
        console.log(x);//255

        //2. Number.isFinite 检测一个数值是否为有限数
        console.log(Number.isFinite(100));//true
        console.log(Number.isFinite(100/0));//false
        console.log(Number.isFinite(Infinity));//false

        //3. Number.isNaN 检测一个数值是否为NaN
        console.log(Number.isNaN(123));//false

        //4. Number.parseInt Number.parseFloat字符串转整数
        console.log(Number.parseInt('5211314love'));//5211314
        console.log(Number.parseFloat('3.1415926神奇'));//3.1415926

        //5. Number.isInteger 判断一个数是否为整数
        console.log(Number.isInteger(5));//true
        console.log(Number.isInteger(2.5));//false

        //6. Math.trunc 将数字的小数部分抹掉
        console.log(Math.trunc(3.5));//3

        //7. Math.sign 判断一个数到底为正数 负数 还是零
        console.log(Math.sign(100));//1
        console.log(Math.sign(0));//0
        console.log(Math.sign(-2000));//-1
    </script>
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